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Being from Los Angeles, our first glimpse of BMW‘s brand-new ber wind tunnel complex in Munich had an oddly familiar look to it. Frank Gehry architecture! Of course it isn’t, but the undulating structure — think of a gigantic snake eating its own tail — is clad in the same sort of complex polished metal panels that compose Gehry’s Walt Disney Music Hall in downtown L.A. Personally, I think it’s no less attractive.

Our in-depth tour of the facility was the feature event of a two-day technical program BMW hosted to offer insights into its latest work in aerodynamics, engine and transmission design, capped by a drive of the new xDrive-equipped 7 Series in the south of France. And while BMW’s umbrella title tying these diverse topics together is “Efficient Dynamics,” mine was “Really Cool Stuff.” With the coolest, in my opinion, being our visit to the wind tunnel, which BMW more precisely calls its Aerodynamic Test Center.

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Actually, there are two tunnels here. The big one is laid out in a horizontal rectangle, while the second, smaller tunnel — which was created for scale model testing and advanced experimental work — is folded vertically atop itself and nestled within the donut hole of the first tunnel. Why the compactness? Munich property values. (Nevertheless, it employs a workforce of 500.)

Now, before you start thinking “yikes, here comes a tedious story about wind tunnels,” well, you really have to see a modern, giant wind tunnel first. They’re truly among the world’s great guy-toys. If I were Bill Gates, I’d have one of these in the backyard in a second. No, a millisecond. Imagine: hurricane-wind speeds, humongous propellers, smoke trails, the ever-present threat of slipping into its bowels and coming out hamburger. (Actually, several screens prevent this, but it still wouldn’t be fun getting pinned against a metal mesh by this one’s 186-mph wind blast.) What’s not to like? And, hey, as a member in bad standing of the Chrysler-Desoto Airflow Club (need to pay those dues), wind tunnels are sort of quasi-cathedrals in my book.

BMW’s twin tunnel complex replaces the original tunnel built in the late 1970s, several inconvenient miles from Munich. But beyond their shiny newness, a couple of technical features make each of these tunnels unique. However, it should be noted that the big tunnel would be one of the world’s premier venues for automotive aerodynamics testing due to the sheer giganticness of its cross section.

Why does size matter? The most trustworthy test numbers (Cd, and lift on the front and rear axles) come only when a car’s blocking effect — i.e., the test car’s frontal area relative the tunnel’s — is absolutely minimized. Yet it also offers a 10 meter-long moving ground plane (a giant steel band on two big rollers) beneath the car, along with a slit-like scoop that sucks away the floor’s turbulent boundary layer just before the belt.

Additionally, both tunnels feature a novel assemblage of mammoth and adjustable airfoils at the conclusion of test section that produce a notably consistent upstream pressure distribution in the vicinity of the test car (better mimicking the real world). We were told that a Cd measurement in this tunnel is probably within 1/100th of what would be produced by an ideal tunnel having infinite size.

Meanwhile, the sensitivity of its scales is such that they could detect even the weight of a paper airplane resting on the test car. Why so sensitive? If you can detect minor aerodynamic imperfections at several locations around the bodywork — and then eliminate them — their sum can add up to a tidy drag reduction.

The smaller tunnel is no less interesting. Here, half-scale models are tested, also on a moving ground plane. But while you’d think the half-scale models would imply similarly lower wind speeds, a pesky rule of aerodynamic scaling (the Reynolds Number!) actually requires the wind speed to be doubled, so this has to be a very high-speed tunnel as well. A particularly neat capability of the smaller tunnel is its ability to maneuver two models around on the moving ground (suspended from twin overhead gantries) while the fan is running, to explore the aerodynamic interaction of cars running nose to tail, or even passing each other.

While the tunnel was intended for models, full-sized cars can be tested as well. I was intrigued to learn that when they are, vertical loads on the wheels are measured by repositionable load cells beneath air bearings that support both the wheels and the fast-moving steel belt.

One interesting aerodynamic nugget that came to light during our conversations was that while a car’s bodywork is certainly the greatest source of aerodynamic resistance, it isn’t the dominant as you might think. Indeed, it accounts for only about 40% of the total, with 30% arising from the wheels and wheel wells, 20% from the car’s underbody, and 10% owed to internal air flow (radiator flow and whatnot).

Another morsel: If you can reduce air resistance by 10%, fuel consumption declines by about 2.5 %. And speaking of that startlingly high wheel-well resistance number, the small tunnel’s role in experimental, and early-on, development was illustrated by a concept we were shown called an “air curtain.” Here, the front air intake of a 50% model of a 3 Series was internally ducted such that its flow was expelled in a sheet from the half of the wheel well, smoothing over the turbulence typically created by the front wheels as it passes.

Finally, when I asked whether all this could really be accomplished by computational fluid dynamics, the reply was “Well, the two approaches work hand in hand.” Actually, the main value of the tunnel is that it is quicker to get a result from, because several shapes can be evaluated per day in the tunnel, while computer speed limits a computational result to one every day or so. Personally, though, I think they just love gigantic wind tunnels as much as I do.

New Engines and An Eight-speed Transmission

In a presentation room BMW also displayed some of its latest engine and transmission work. On the gas-engine front, its 3.0-liter six will for the first time employ BMW’s holy trio of power and efficiency-enhancing technologies — Valvetronic, a single but twin scroll turbocharger (whose turbine is separately impinged by the exhaust of the first three and last three cylinders), and direct injection.

The new “TwinPower Turbo” engine’s combination of technologies produces 306 hp at 5800 rpm and 295 lb-ft at 1200 rpm of torque, the same output as the current twin turbo, though the torque peak occurs slightly sooner. What’s significant is its 9% reduction in fuel consumption and 9-lb. lighter weight. What’s made all this possible is the full integration of the Valvetronic mechanism into the head’s design, such that direct injection can be fitted in as well.

Also shown was a Europe-only 3.0-liter inline-six diesel featuring two turbochargers (a big one and a small one), electrically controlled variable geometry (on the small one), various valves to direct the gas flow in umpteen different ways, and consequent plumbing that looks like it was penned by M.C. Escher.

The example on display was one of those mazes of pipes and elbow connections that leaves thinking to yourself, “yeah, right.” If Germans love complex technology, this baby takes the schnitzel. Its basic idea is that at low-exhaust gas flows, the little turbo acts alone. As the power demand rises, the second spinner comes into play, but the pair’s overall response is fine-tuned by the little guy’s quick-responding variable geometry. At high power, all of the intake air compression is performed by the big turbo. The result is 306 hp at 4400 rpm, and 442 lb-ft or torque at 1600 rpm, 61 hp and 44 lb-ft greater torque than its predecessor.

Introduced with the V-12 engine in 760i, the new eight-speed automatic transmission represents a credible alternative to the hoopla over dual-clutch trannies. It’s virtually the same weight as its six-speed predecessor, can shift with double-clutch rapidity (sometimes even faster, says BMW), and has been so cleverly designed by BMW and ZF that it requires the same number of clutches. A myriad of operational refinements means it’s also 6% more efficient and easily capable of accepting an electric motor when the hybrid need arises, or perhaps an Auto Stop/Start capability (mentioned as a possibility with the 3.0-liter gasoline engine).

750i xDrive

And lastly, we drove the new 750i xDrive in various test scenarios at BMW’s sprawling Miramas test facility outside of Marseille. While it shares a lot in common with BMW’s xDrive AWD applications already seen on the 3 and 5 Series, its operation has undergone a lot of rethinking.

Previously, the front/rear torque split of, say, the 535i xDrive was relentlessly held at around 40/60, unless problematic understeer or oversteer was discerned. With the 750i xDrive (AWD’s first 7-Series appearance, by the way) its nominal 40/60 split can fluidly change to 20/80 as you transition to the middle of a corner, the result being a sensation of less understeer and more steering authority.

Realize, too, that this occurs during perfectly normal driving. If understeer does develop, a system already available on the rear-drive 750i can lightly drag the inside rear wheel’s brake while carefully adding power to the rear axle so you don’t detect any braking effect. If oversteer occurs, the 20/80 torque split reshuffles more power to the front wheels. And on top of all this, the car’s adjustable front and rear anti-roll bars (already a feature of the rear-drive 750i) can redial the big sedan’s orientation as well.

It’s a potent three-layer strategy that BMW’s chassis engineers can mix and match at will, depending on the circumstances. A couple of interesting details are that at low speeds (parking lots) all of the power can be directed aft to avoid crabbing, while if the rear wheels happen to be sitting on a patch of ice at a stoplight, the hydraulic center clutch can lock, dispatching all of the engine’s available power to the front wheels.

On a sprinkler-soaked test loop, the 750i xDrive was not only enormously faster than a rear-drive version offered for comparison, but you could really drive it — seriously play with under and oversteer. In the same corners, the standard car was luridly unpredictable, while a 535i xDrive was quick but noticeably understeer-prone. In the 750i’s case, its xDrive redistributes about 1% of the car’s weight distribution to the front axle, increases total weight by roughly 185 pounds, and will have the same cost premium as other xDrive applications, about $2300.

After two days of this rapid-fire blasting with technological information, BMW’s “Efficient Dynamics” show-and-tell made clear that here’s a company stamping its technological throttle to the floor just as some others are pinching pennies and feathering back their engineering aspirations. To them I say, good luck.